Washington Post politics reporter David Fahrenthold didn't set out to investigate Donald Trump's charitable giving, but a curious incident during Trump's presidential campaign piqued his curiosity and led to a powerful series of stories and ultimately, the Pulitzer Prize.

It started on Caucus Day in Iowa in 2016. Fahrenthold, who had been tracking other candidates, decided to cover a Trump campaign rally. In the middle of the rally, Trump produced a giant check, the kind you see handed to winners of golf tournaments. The check was made out to a local veteran's charity for $100,000 from the Donald J. Trump Foundation. There was just one problem. Those kinds of donations by candidates are not legal.

That donation led to Fahrenthold's ongoing investigation into Trump's charitable activities. In 2017, Fahrenthold won a Pulitzer Prize in National Reporting for this work.

As part of MPR's Broadcast Journalist Series, MPR News Executive Editor Mike Edgerly interviewed Fahrenthold at the University of St. Thomas on April 30, 2018.